Abstract: An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created, and subsequently detected, at plural locations within the disk by an electro-optical head. Creation and detection of holographic gratings with variable diffraction efficiency is possible with the electro-optical head. Multiple holographic gratings can also be created at each one of the plural locations via a beam of light which has a different wavelength or point of focus. These data elements can be read by the electro-optical head using a beam of light sequentially varied in wavelength or point of focus to correspond to the multiple holographic gratings to be recorded.

Abstract: A system of reproducing multiplexed holographic information from one master medium (100, 300, 400, 500, 600, 720) to another replicate medium (200, 310, 410, 510, 610, 730) simultaneously reads out the information from all multiplexed master holograms within the master medium. The replica has different phase and amplitude distributions from the master medium containing a plurality of multiplexed holograms (420, 520) though both the replica and the master contain the identical holographic information of the original objects.

Abstract: An optical memory for storing and/or reading data on an optical disk. The optical disk incorporates a material in which holographic gratings can be created at plural locations within the disk. An electro-optical head which is capable of creating these holographic gratings at any one of the plural locations is employed. The head is additionally capable of detecting the presence or absence of a holographic grating at any one of these plural locations. The presence of the holographic grating could indicate a first binary state and the absence of the holographic grating indicate a second state. Alternately, the electro-optical head could be used to vary the diffraction efficiency of the holographic gratings during their creation. In that case, the head would also be capable of detecting this variation in efficiency and produce a proportional detection signal. This signal would be used as an indicator of the value of the stored data element.

Abstract: The invention is embodied in an optical memory having a holographic recording medium capable of storing respective holograms in respective storage spots, the memory including a coherent collimated reference beam and an information-bearing object beam illuminating the recording medium, a segmented optical array including a stack of plural segmented optical sub-arrays, each of the segmented optical sub-arrays including an array of generally parallel optical strips, each optical strip having a strip length extending parallel to the optical strips, respective optical strips of all of the sub-arrays providing an optical path for the reference beam to respective recording spots in the holographic recording medium whenever the reference beam is incident within the strip length, two optical strips in different sub-arrays with optical paths to the same recording spot being separated by at least an out-of-plane multiplexing difference angle subtended by paths of the reference beam to the two optical strips, a reference

Abstract: Disclosed is a spatial multiplexer for use with a holographic storage medium, and an information storage system employing the spatial multiplexer. The spatial multiplexer directs a reference beam of optical radiation onto the storage medium, the storage medium having (n) rows and (m) columns of storage locations. The spatial multiplexer includes an array of (n times m) discrete reflector elements each having a linear shape. The discrete reflector elements are disposed in a parallel arrangement with one another upon a substrate, and each has a different angular orientation with respect to the storage medium. A deflection of the reference beam by an angle multiplexer changes the angle of incidence of the reference beam on the storage medium, which provides multiple angles required for angle multiplexing a plurality of superimposed holograms within a single storage location.